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Kinetics of iron oxidation by Leptospirillum ferriphilum dominated culture at pH below one
Author(s) -
Özkaya Bestamin,
Sahinkaya Erkan,
Nurmi Pauliina,
Kaksonen Anna H.,
Puhakka Jaakko A.
Publication year - 2006
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.21313
Subject(s) - ferrous , kinetics , chemistry , ferric , reaction rate constant , saturation (graph theory) , nuclear chemistry , analytical chemistry (journal) , inorganic chemistry , chromatography , organic chemistry , physics , mathematics , quantum mechanics , combinatorics
Abstract The kinetics of ferrous iron oxidation by Leptospirillum ferriphilum ( L. ferriphilum ) dominated culture was studied in the concentration range of 0.1–20 g Fe 2+ /L and the effect of ferric iron (0–60 g Fe 3+ /L) on Fe 2+ oxidation was investigated at pH below one. Denaturing gradient gel electrophoresis of PCR amplified 16S rRNA genes followed by partial sequencing confirmed that the bacterial community was dominated by L. ferriphilum . In batch assays, Fe 2+ oxidation started without lag phase and the oxidation was completed within 1 to 60 h depending on the initial Fe 2+ concentration. The specific Fe 2+ oxidation rates increased up to around 4 g/L and started to decrease at above 4 g/L. This implies substrate inhibition of Fe 2+ oxidation at higher concentrations. Haldane equation fitted the experimental data reasonably well ( R 2 = 0.90). The maximum specific oxidation rate ( q m ) was 2.4 mg/mg VS · h, and the values of the half saturation ( K s ) and self inhibition constants ( K i ) were 413 and 8,650 mg/L, respectively. Fe 2+ oxidation was competitively inhibited by Fe 3+ and the competitive inhibition constant ( K ii ) was 830 mg/L. The time required to reach threshold Fe 2+ concentration was around 1 day and 2.3 days with initial Fe 3+ concentration of 5 and 60 g/L, respectively. The threshold Fe 2+ concentration, below which no further Fe 2+ oxidation occurred, linearly increased with increasing initial Fe 2+ and Fe 3+ concentrations. Fe 2+ oxidation proceeds by L. ferriphilum dominated culture at pH below 1 even in the presence of 60 g Fe 3+ /L. This indicates potential of using and biologically regenerating concentrated Fe 3+ sulfate solutions required, for example, in indirect tank leaching of ore concentrates. Biotechnol. Bioeng. 2007; 97: 1121–1127. © 2006 Wiley Periodicals, Inc.